The number and types of electronic devices available to consumers have increased tremendously the past few years and this increase shows no signs of abating. Electronic devices such as portable computing devices, tablet, desktop, and all-in-one computers, smart phones, storage devices, portable media players, navigation systems, monitors, and other devices have become ubiquitous.
The functionality of these devices has increased as communications, global positioning, graphics, and other types of circuits have been added. At the same time, these electronic devices have been getting smaller. As a result, the functional density of these electronic devices continues to increase.
Much of the increase in functional density that has been achieved is due to the increase in functionality of integrated circuits and modules, particularly with system on an integrated circuit (SOIC), system in package (SIP) modules, and other high-density circuits. These circuits and modules are often connected to printed circuit boards through an array of contacts, for example by a ball grid array (BGA.)
The contacts of a BGA may be soldered to contacts on a printed circuit board of the electronic device. The printed circuit board contacts may connect to traces in the printed circuit board. These traces may form electrical pathways for signals and power.
It may be difficult to route these traces in an area below an SOIC, SIP, or other high-density circuit. Specifically, while a printed circuit board may contain several layers on which traces may be routed horizontally, it may be difficult to form the necessary vertical paths. Typically, vias are used, but the required spacing between vias may be large enough that forming a sufficient number of vias may be problematic.
Thus, what is needed are printed circuit boards having an increased density of vertical interconnect paths, as well as methods for their manufacture.